The art of archery has progressed to a point where sophisticated archery equipment is now available and in use for a variety of functions. Generally, compound bows are formed by a pair of bow limbs which are joined at their inner ends to a handle section. The outer ends of the limbs are bifurcated and are provided with an eccentric pulley mounted in the bifurcated portion thereof. In the compound bows presently available, one end of the bow string is mounted to the interior surface of one of the bow limbs, and is then carried around a first idler wheel positioned between the mount point of the bow string on the limb and the outer end of the limb, and is then carried about the opposed eccentric pulley mounted on the opposed bow limb end, crossed back over the opposed eccentric pulley mounted on the opposed limb end, thence down around a second idler wheel such that the opposed end of the bow string is then mounted to the interior surface of the second bow limb at a mount point positioned between the junction of the bow limb with the handle section and the second idler wheel. It should be understood that where reference is made to the mounting of the bow string to the interior surface of the bow limbs, it will be understood that such mounting may be either to the bow limbs or the handle section or a combination of both. In addition, where reference is made to a bow string, it should be understood that this phrase applies equally to a cable arrangement or a combination of bow cables and bow strings.
The primary function and advantage achieved by a compound bow is to increase the arrow speed and impact by providing a bow which, for a given holding strength, is capable of storing greater energy when drawn to the full draw of the bow. The provision of opposed offset pulleys mounted in the bifurcated ends of the bow limbs has the effect of providing a lesser pull weight at full draw than is required to pull the bow string through an intermediate drawn position. Another advantage which follows is that the force applied by the archer to draw the bow string through the intermediate drawn position is greater than the force required to hold the bow string in the fully drawn position such that it is possible for the archer to maintain the bowstring in the drawn position without exerting the same great degree of force. Exemplary of a prior art patent which illustrates a compound bow is U.S. Pat. No. 3,486,495.
In understanding further improvements related to compound bows, it is also necessary to appreciate the fact that the forces causing the flexing/bending of the compound bow occur at two major points on each limb; one of the points is at the tip end of each of the limbs where the eccentric wheel is positioned, and the other is at a point further down the limb where the idler wheel is attached to the bow limb. In presently existing compound bows, and as indicated previously, the ends of the bow strings are attached to the interior surfaces of each of the bow limbs. However, it is known that the force incident to the idler wheel is a major source of the mechanical advantage which makes a compound bow superior to a regular bow. Hence while the force at the tips of the bow limbs is relatively constant, it is the force of the idler wheels which effect the efficiency, control, and ultimately, the thrust on the bowstring and ultimately the arrow. The foregoing results from the fact that the direction of the force applied to the limb at the idler wheel lies primarily along the direction of the cable or bowstring from the idler wheel to the point where the bowstring attaches to the handle or bow limb. It will therefore be appreciated that if the bowstring is attached to the interior surface of the bow limbs, the perpendicular force is less and the parallel force is greater thus affecting the efficiency, control, and velocity incident to the thrust of the bowstring when released.